In the process of drilling for hydrocarbons such as oil and natural gas, vertical wells have been used most often in the past. Those wells will produce for a given amount of time, then begin to dry up. At that point, it is advantageous to drill out horizontally from the vertical well in order to try and increase production of, for example, crude oil.
There have been several attempts to find an economically viable and reliable system for drilling into the untapped pay zones adjacent an existing vertical well. Horizontal drilling has been proposed as an alternative and has been described in U.S. Pat. Nos. 5,853,056, 5,413,184, 5,934,390, 5,553,680, 5,165,491, 5,458,209, 5,210,533, 5,194,859, 5,439,066, 5,148,877, 5,987,385, 5,899,958, 5,892,460, 5,528,566, 4,947,944, 4,646,831, 4,786,874, 5,410,303, 5,318,121, 4,007,797, 5,687,806, 4,640,362, 5,394,951, 1,904,819, 2,521,976 and Re. 35,386, the contents of all of which are incorporated herein by reference.
U.S. Pat. No. 5,413,184 describes a method of horizontal drilling which utilizes a flexible hose and a high pressure nozzle blaster to bore into the earth's strata at significant depths, such as 4000 feet. The nozzle uses high pressure water to clear a path through the strata. The nozzle is advanced through the strata by applying weight to the hose, i.e., slacking off the tension in the vertical portion of the hose. Essentially, the weight of the 4000 feet of hose above the nozzle is used to apply pressure to the nozzle, thus forcing it along the horizontal path. While this method is effective at significant depths due to the large amount of weight available, it is less effective at shallower depths. At shallow depths, there simply is not enough weight available to supply sufficient force to advance the nozzle blaster through the strata. Thus, there is a need for an apparatus that will effectively advance a drilling tool such as a nozzle blaster horizontally through the earth's strata for horizontal drilling at shallow depths. Moreover, as horizontal or lateral hoses extend further from the bore hole, removal of cuttings by using sequential thrusters with the ability to shut off unnecessary jets is desired so that more fluid is directed at desired thrusters and volume of fluid is increased for cleaning purposes. This arrangement can also be used for cleaning obstructed pipes such as those in power plants.